Commercial automated dishwashers have been used for many years in a variety of different locales, wherever large amounts of cookware, silverware, dishware, glasses or other ware need to be cleaned and sanitized. Regardless of whether the dishwasher in question is a simple batch loading dishwasher or a complex multi-stage machine, there is an on-going problem with heated water vapor escaping the machine at the end of a cleaning program. This heat and humidity comes into direct contact with the kitchen personnel and generally reduces comfort of the kitchen environment. Commercial dishwashing machines can heat water or utilize very hot water from other sources, especially in the final rinse stage, to help ensure cleaning and sanitation. Current dishwashers are classified as either high temperature machines or as low temperature machines, based on final rinse water temperatures. The high temperature machines have a final rinse water temperature of at least about 180.degree. F. while the low temperature machines have a final rinse water temperature of about 160.degree. F. Such high temperatures are necessary to ensure adequate sanitization of the dishes or other ware being cleaned. The high temperature rinse allows for one-step sanitization whereas the low temperature rinse is typically accompanied by an additional chemical (chlorine, peracid, etc.) sanitization addition step. In either situation, hot ware and significant volumes of heated, highly humidified air are created in the dishwasher, particularly as a result of the final rinse, which is typically the hottest step in the dish or warewashing process.
Direct contact with hot, humid air can pose safety problems. The humidity causes significant safety problems for people who wear glasses and/or contact lenses. The hot, humid air can irritate people without eyewear as well. Significant amounts of heated water vapor are put into the room environment, straining air conditioning systems and generally creating discomfort for operators. Further, the dishes removed from the dishwasher can be at high temperature.
One way to address these difficulties concerns the use of vent hoods to capture the hot, highly humid air escaping from the dishwasher upon opening. A drawback to this method is that the hot, highly humid air contacts environmental air in the use locus and the hood removes only a portion. As a result, some heat and humidity is transferred to the immediate environment. While the hood will draw the hot, highly humid air up and away from the dishwasher, it may fail to completely protect the operator from contact with heat and humidity. In addition, hoods are large, noisy and expensive, wasting heat during winter months, and conditioned air in summer months. Further, such a system requires venting to the exterior of the building. Another way to address these problems concerns the use of electric exhaust fans to remove the heat and water vapor. Unfortunately, this is noisy, requires electricity and means to vent to the exterior of the building. In addition, this also requires a separate means to cool and condense the water vapor. EP 0 753 282 A1 deals with the problem of hot water vapor by cooling and condensing the steam released from the dishwasher. This is accomplished by directing the steam through a heat exchanger through which cold water is circulated. However, this device is limited to applications in which the wash chamber is sealed. Such a device would not work, for example, in a single-stage or multi-stage dishwashing machine open to the atmosphere. EP 0 721 762 A1 teaches the use of a fan to pull the steam into a condensation chamber in order to prevent the escape of moisture to the immediate environment. Of course, this method requires the use of a fan, which adds expense, complexity and noise to the dishwashing apparatus.
Therefore, a need remains for a simple, inexpensive and unobtrusive means for capturing the water vapor released from commercial dishwashers.